Biology Circulation / Transport NUMS 2022
PMDC Verified Question 31 of 54
Heart beat is normally regulated by:
A
Purkinje fibres
B
AV-bundle
C
SA-node
D
Bundle of His
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: SA-node
Concept:

Heart rate regulation is intrinsically controlled by autorhythmic cells.

Formula:

None

Solution:

  • The Sinoatrial (SA) node possesses the fastest intrinsic rate of spontaneous depolarization.


  • It functions as the heart's natural pacemaker, initiating the action potential and thus regulating the normal heartbeat.


Why other options are incorrect:

  • While the AV-bundle, Purkinje fibers, and Bundle of His conduct the impulse, they do not establish the primary rhythm under normal physiological conditions.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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